Factors Influencing the Performance of the Precipitin Test in the Determination of Blood Meals of Insects

Certain factors influence the performance of precipitin tests when the latter are used for detection of blood meals of biting flies. Antisera stored in a liquid state in a refrigerator generally show a decrease in titer with the passage of time. Aging appears to have an adverse effect on the avidity of an antiserum. Smears of blood-engorged mosquitoes prepared by smearing of the entire insect are satisfactory for testing by the precipitin reaction. A high-titered antiserum which can be diluted is desirable for detection of host blood in mosquitoes.